Workouts Cut Prostate Cancer Risk in Whites

Action Points

Note that this prospective cohort study suggests an association between self-reported activity levels and risk of prostate cancer among white men undergoing prostate biopsy.

Be aware that activity levels were determined by self-report.

Another benefit of exercise – at least for Caucasian men – is that it may cut the risk both of developing prostate cancer and having high-grade disease, researchers reported.

In a prospective study, Caucasian men suspected of prostate cancer and scheduled for biopsy were less likely to have the disease if they were at least moderately active, according to Lionel Bañez, MD, of the Durham Veterans Affairs Medical Center in Durham N.C., and colleagues.

If they did have cancer, they were significantly less likely to have high-grade disease if they had been working out regularly, Bañez and colleagues reported online in Cancer.

On the other hand, exercise was not associated with prostate cancer risk among black men, or with the risk of high-grade disease, the researchers found.

The reasons for the disparity remain unclear, although Bañez and colleagues noted there are several possible mechanisms that might play a role, including hormonal profiles and genetic susceptibilities that differ between races.

"Further studies are needed to investigate the mechanism behind this racial disparity in deriving cancer-related benefits from exercise which disfavors African American men," Bañez said in a statement.

He and colleagues looked at results, stratified by race and exercise levels, of biopsies for 307 men suspected of prostate cancer.

Exercise, assessed by a questionnaire before the procedure, was broken into four categories of metabolic equivalent (MET) hours per week: fewer than 3 was sedentary, 3 through 8.9 was mildly active, 9 through 17.9 was moderately active, and 18 or more was highly active.

The study cohort included 164 white men and 143 blacks, with average age of 64. There was no difference between the racial subgroups in the amount of exercise, Bañez and colleagues found.

The biopsies found cancer in 125 men, including 54 who had high-grade disease, they reported.

Multivariate regression analysis showed that, when exercise was treated as a continuum, it did not predict a positive biopsy in the overall cohort or among the black subgroup.

But among the Caucasian participants, the odds ratio for a positive biopsy was 0.90 (95% CI 0.82 to 1.00, P=0.04).

In multivariate regression analysis based on different levels of exercise, using the sedentary group as a reference, Caucasian men who were at least moderately active – with more than 9 MET hours a week – had an odds ratio for a positive biopsy of 0.47 (95% CI 0.22 to 0.99, P=0.047).

Again, there was no significant benefit for any level of exercise among the black participants, Bañez and colleagues found.

Among the men with cancer, they found an inverse relationship between exercise and the risk of high-grade disease (OR 0.87, P=0.01).

Further analysis, as a function of race, showed that the relationship remained significant only among the white participants.

The researchers cautioned that the cohort was small, which raises the possibility that the findings are the result of chance. In addition, factors that were not measured, such as diet, might have played a role, they added.

Bañez and colleagues also pointed out that the questionnaire, although a validated instrument, did not specify the exact time frame meant by the word "current" when it asked about "current exercise," and "is therefore subject to the participant's interpretation."

The journal said no specific financial support was disclosed and the authors made no conflict of interest disclosures.

Reviewed by F. Perry Wilson, MD, MSCE Instructor of Medicine, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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